The difference is Zurvu actually partners with the restaurants, helping them move empty tables. They may request a certain number of tables be free per night, but because they partner with the restaurants (that they prominently display), that presumably comes with kickbacks to the restaurant in question.
And Killer Rezzy's goal is to allow restaurants to monetize reservations. While this may suck for those of us who don't want to pay an entrance fee to eat, it's certainly not harming the businesses they depend on.
This seems taken out of context. I don't think he was making a blanket statement, he was asking if people are willing to pay for this particular service, is it unethical? Ie, is it reasonable to say that if people are willing to pay for restaurant reservations, specifically, does that say anything about the ethics of it. Not to say that it is a good point, but I don't think it's some moral statement that paying for something makes it de facto ethical in general.
"To be honest, I haven’t spent a lot of time thinking through these questions." http://brianmayer.com/2014/07/how-i-became-the-most-hated-pe...